1. Field of the Invention
The present invention relates to a sample holder unit that holds a sample to be used in an ion milling apparatus, and to a sample observation apparatus including the sample holder unit.
2. Description of the Related Art
In general, a sample observed under an electron microscope is etched with an ion beam emitted from an ion milling apparatus and is processed into a shape that is suitable for observation. Prior to the processing with the ion milling apparatus, the sample that is held by a sample holder is positioned relative to a shielding plate that blocks the ion beam.
A technique of positioning a sample to be processed and a shielding plate is disclosed by Japanese Unexamined Patent Application Publication No. 2007-14996. The technique employs a sample-mask unit that holds a sample, and a securing table on which the sample-mask unit is placed. The sample-mask unit to be placed on the securing table can be set obliquely with respect to the optical axis of an optical microscope under which a sample is to be observed.
In the technique disclosed by Japanese Unexamined Patent Application Publication No. 2007-14996, however, the angle of inclination of the securing table is specified. That is, the sample is observable only at the specified angle of inclination with respect to the optical axis of the optical microscope, which is an exemplary observation unit. Therefore, the technique has a problem in that it is impossible to observe the sample at an arbitrary angle of inclination with respect to the optical axis of the observation unit.